Home Run Hitting in Statcast Era

Jim Albert

Introduction

  • There has been remarkable changes in home run hitting during the Statcast period 2015-2025

  • What variables influence home runs?

  • We will focus on two reasons – batter behavior and ball construction

Data

  • Focus on the balls in play

  • I have data on all balls in play for all Statcast seasons

  • Home run rate is \[ HR \, \,Rate = 100 \, \frac{HR}{BIP} \]

Balls in Play (BIP) and Home Runs (HR) by Season:

Season BIP HR HR_Rate
2015 129691 4866 3.75
2016 128826 5610 4.35
2017 127555 6105 4.79
2018 126282 5585 4.42
2019 125751 6776 5.39
2020 43972 2304 5.24
2021 121706 5944 4.88
2022 124221 5215 4.20
2023 124199 5868 4.72
2024 124078 5451 4.39
2025 124833 5648 4.52

In-Play Home Run Rates

Process of Hitting Home Run

  • Hit the ball well (hard and at right angle)
  • Given that the ball is hit well, the ball has to leave the park

What is a Launch Angle?

Launch Angle measures the vertical angle, in degrees, at which the ball leaves a player’s bat after being hit.

  • Ground ball: Lower than 10 degrees
  • Line drive: 10-25 degrees
  • Fly ball: 25-50 degrees
  • Pop up: Higher than 50 degrees

What is Exit Velocity?

  • Exit Velocity measures the speed of the baseball as it comes off the bat, immediately after a batter makes contact. This is tracked for all Batted Ball Events – outs, hits and errors.

  • Attaining a high Exit Velocity is one of a hitter’s primary goals. A hard-hit ball won’t always have a positive result, but the defense has less time to react, so the batter’s chances of reaching base are higher.

Where is launch space where home runs are hit?

Focus on Two Rates

  • Red Rate - the rate of balls in play in the RED region

  • HR Rate - among all the balls in the RED region, what percentage are home runs?

  • The Red Rate tells us about player behavior, the HR rate tells us about the ball (its carry properties)

Add to Table

Season BIP HR RED HR_red
2015 129691 4866 9356 3844
2016 128826 5610 10085 4414
2017 127555 6105 10176 4733
2018 126282 5585 10730 4376
2019 125751 6776 11745 5339
2020 43972 2304 4271 1822
2021 121706 5944 11736 4556
2022 124221 5215 11795 4124
2023 124199 5868 12277 4640
2024 124078 5451 12140 4309
2025 124833 5648 12763 4417

In-Play Red Rates

What have we learned?

  • Players are getting bigger and stronger
  • They work on hitting balls on “HR friendly” launch angles
  • So there has been a steady increase in RED rates

Home Run Rates in Red Region

What have we learned?

  • The increase on home run rates depends on more than the players
  • The changes in the RED HR rates reflects properties of the ball
  • Some seasons, the ball is lively
  • Recently, the ball has been relatively dead
  • This impacts records like Aaron Judge’s 62 HR in 2022

Does MLB Care?

  • During the big increase in HR hitting, MLB created a committee to study the issue
  • Committee made some recommendations
  • I don’t think home run hitting is one of the big issues currently

Statcast HR Hitting